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UNITED STATES DEPARTMENT OF AGRICULTURE 




BULLETIN No. 508 



Contribution from the Forest Service 
HENRY S. GRAVES, Forester 




Washington, D. C. 



PROFESSIONAL PAPER 



March 6. 1917 



YIELDS FROM THE DESTRUCTIVE DISTILLATION 
OF CERTAIN HARDWOODS. 

SECOND PROGRESS REPORT. 

By R. C. Palmee, Chemist in Forest Products. 



CONTENTS. 



Purpose of experiment 

Plan of investigation 

Method of recording data 

Yields on per cent weight basis . 



Yields per cord 

Pyroligneous acid, tar, and charcoal . 
Commercialdistillation 



PURPOSE OF EXPERIMENTS. 

The object of the investigations reported in this bulletin and in 
Bulletin 129, to which this is supplementary, was to determine the 
relative value of the various hardwoods commonly used for de- 
structive distillation, and of the different forms of material, such as 
bodywood, limbs, and slabs. The experiments were carried on at 
the Forest Products Laboratory, maintained at Madison, Wis., in 
cooperation with the University of Wisconsin. The standard 
species — beech, birch, and hard maple — were included in the labora- 
tory tests so as to make the results on other species comparable with 
them and hence commercially applicable. Bulletin 129 gives the 
yields for these three standard species, and, in addition, red gum, 
chestnut, hickory, white oak, and tupelo. The present bulletin gives 
the yields for white elm, slippery elm, silver maple, green ash, blue 
ash, yellow ash, chestnut oak, tanbark oak, California black oak, 
Louisiana swamp oak,^ and eucalyptus. 

The results here reported are of most value when compared with 
laboratory distillations of species whose yields in commercial prac- 

1 " Swamp oak " was a mixture of laurel, post, water, willow, Spanish, and cow oaks, 
usually growing in mixed stands. Acknowledgment is made of the assistance of Mr. H. 
Cloukey in analyzing some of the distillates. 

Note. — This bulletin gives the results of experiments in destructive distillation of 
hardwoods and is of interest to manufacturers of by-products. 
70252°— Bull. 508—17 



2 BULLETIN 508, U. s. DEPARTMENT OF AGRICULTTJRE. 

tice are well known. Laboratory methods of distilling are not com- 
parable directly with commercial conditions, and the calculated 
yields per cord from laboratory distillations on 100 or 200 pounds of 
material are frequently much higher than the yields from distilling 
several thousand pounds in the commercial plant. 

PLAN OF INVESTIGATION. 

The apparatus used and the manner of making the tests are de- 
scribed in Bulletin 129. Both body and slab wood were distilled in 
most cases and in a few species limb wood was included in the study. 

The yields of wood alcohol and acetic acid were determined by 
analysis of the pyroligneous-acid liquor/ and the amount of tar and 
charcoal was determined by measurement. The average was taken 
of three or four tests on each form of material. 

METHOD OF RECORDING DATA. 

The yields are expressed in three ways: (1) As a proportion of the 
oven-dry weight of the wood distilled (it is only on this basis that 
the results are independent of varying percentages of moisture in 
the material and of differences in the weight of unit volumes) ; (2) 
in the commercial units, gallons of 82 per cent crude wood alcohol 
and pounds of 80 per cent gi^ay acetate of lime per cord of air-dry 
wood; 2 and (3) as a proportion of the yield of a cord of equal parts 
of beech, birch, and maple. 

YIELDS ON PERCENTAGE WEIGHT BASIS, ALCOHOL AND ACETIC 

ACID. 

VARIATION AMONG SPECIES. 

The average yields of acetic acid and wood alcohol expressed in 
percentages based on the oven-dry weight of the material distilled 
are given in Table 1. The yields from a previous study of the 
standard species, beech, birch, and maple, are given for comparison. 
On this basis several of the species tested compare very favorably 
with the standard species. White elm, slippery elm, silver maple, 
and black ash gave nearly the same yields of alcohol as beech and 
hard maple. The acetic-acid yield of white elm, silver maple (heart- 
wood), tanbark oak, and California black oak (limbs) were very 
nearly the same as that of birch, and considerably larger than the 
yield of beech and maple. 

1 The methods of analysis are given in Klar's Technologie der Holzverkohlung, p. 337, 
except that in the alcohol analysis a final distillation is made after adding a few cubic 
centimeters of concentrated H0SO4 to eliminate the wood-oil constituents. 

~ A cord of air-dry wood is assumed for purposes of comparison to be equal to 90 cubic 
feet of solid wood containing 15 per cent moisture (calculated on the dry weight). The 
weights per cubic foot of wood are those given in " The Principal Species of Wood," by 
C. H. Snow. Recent investigations by the Forest Service show weights per cubic foot 
slightly different from those used in these calculations, but the relative values are not 
changed. 



YIELDS FROM DISTILLATION OF CERTAIN HARDWOODS. 



Table 1. 



■Yields of alcohol and acetic acid in percentages 'based on the oven- 
dry weight of the material distilled. 





Locality. 


Wood 


alcohol 
cent). 


(100 per 


Total acetic acid. 


Species. 


Heart- 
wood. 


Slab- 
wood. 


Mean 
heart- 
wood and 
slabwood. 


Heart- 
wood. 


Slab- 
wood. 


Mean 
heart- 
wood and 
slabwood. 


Beech 


Indiana 


Per ct. 
1.95 
1.45 
1.94 
2.12 
2.03 
1.89 
1.91 

1.79 


Per ct. 
1.79 
1.55 
1.91 
1.68 
1.79 
1.77 
1.43 

2.04 


Per ct. 
1.87 
1.50 
1.93 
1.90 
1.91 
1.83 
1.67 

1.91 

2 2.02 

1.27 


Per ct. 
5.56 
6.71 
5.42 
6.39 
5.77 
6.30 
4.64 

5.65 


Per ct. 
6.18 
6.88 
5.11 

16.61 
5.53 
5.31 
4.14 

5.16 


Per ct. 
5.87 


Birch 




6.80 




do 


5.26 


White elm 


Pennsylvania 


6.50 


Slippery elm 


Wisconsin 


5.65 


Silver maple 


do 


5.81 


Green, blue, and yellow 

ash. 
Black ash 


Tennessee and Mis- 
souri. 
Wisconsin 


4.39 
5.40 


Green ash 




2 4. 51 


Chestnut oak ^ 


Tennessee 


1.22 
1.72 


1.30 


4.88 
6.89 

""4.' 90* 
4.58 


4.91 


4.90 


Tanbark oak 


Cahfomia 




Black oak 


do 


1.53 
1.31 

1.68 


2 1.66 
1.40 
1.50 


6.01 
5.43 
5.31 


2 6.76 


Swamp oak 




1.50 
1.33 




Eucalj'ptus 


California 


4.94 







1 One-third of this sample was slab free from bark, 

2 Limbs. 

3 In case of chestnut oak the mean is not the average, since the slab represented more runs than heart. 

VARIATION DUE TO FORM OF MATERIAL. 

The elms, silver maple, green ash, blue ash, yellow ash, and swamp 
oak gave larger yields of alcohol from heartwood than from slabs, 
but black ash, chestnut oak, and eucalyptus gave the larger returns 
from the slabwood. Chestnut oak, white elm, and eucalyptus slab- 
wood yielded more acetic acid than the heartwood of these species, 
following the tendency previously noted in several other species for 
sapwood to give more acid than heartwood. California black oak 
limbs (practically all sapwood) gave a large yield of acid.^ Silver 
maple yielded more acid from heartwood than from sapwood. 

YIELDS PER CORD, ALCOHOL AND ACETATE. 

COMPARISON OF YIELDS. 

Table 2 is a conversion to a commercial basis of the results given 
in Table 1. The raw material is expressed in terms of cords ^ and 
the products are given in terms of gallons of 82 per cent wood alcohol 
and pounds of 80 per cent acetate of lime. The three standard species 
are again given for comparison. 

The relative yields from the species tested are quite different when 
compared on the cord basis and on the percentage weight basis. 
These differences are, of course, due to the large variation in weight 
per unit volume of the different woods. The two species of elm and 
the silver maple are much lighter woods than beech or hard maple, 
and therefore do not compare so favorably on the cord basis. The 
oaks and eucalyptus are appreciably heavier than the standard 
species, and consequently have a high relative value per cord. 

1 Compare tupelo gum, Bulletin 129. 

- The weights per cord are calculated by multiplying by 90 the known weight per cubic 
foot of air-seasoned material of the species. 



BULLETIN 508^ U. S. DEPARTMENT OF AGRICULTURE. 



Table 2. — Yields of commercial alcohol and acetate per cord of wood. 





Locality. 


Yield of wood alcohol 
(82 per cent). 


Yield of acetate of lime (80 per 
cent. 


Species. 


Heart- 
wood. 


Slab- 
wood. 


Mean 
heart 
and 
slab. 


Heart- 
wood. 


Slab- 
wood. 


Mean 
heart 
and 
slab. 


Weight 

per cord, 

15 per 

cent 

moisture. 


Beech 




Gallons. 
11.8 

8.3 
11.8 
10.2 
10.7 

8.5 
12.1 

10.1 


Gallons. 

10.9 
8.9 

11.6 
8.3 
9.5 
8.2 
9.1 

11.5 
112.8 

8.8 


Gallons. 
11.4 

8.6 
11.7 

9.3 
10.1 

8.4 
10.6 

10.8 

""8.*5* 


Pounds. 
301 
346 
301 
280 
276 
260 
262 

284 
0) 
287 
397 

278 
325 


Pounds. 
335 
355 
284 
290 
263 
219 
235 

260 
257 
291 


Pounds. 
318 
351 
293 
285 
270 
240 
249 

272 

""296' 


Pounds. 
3 785 


Birch 


Wisconsin .. 


3' 600 




do 




White elm 


Pennsylvania 


3,060 
3,330 
2,880 
3,960 

3,510 
3,960 
4 140 


Slippery elm 


Silver maple 


.do... 


Green, blue, and yel- 
low ash. 
Black ash 


Tennessee and Mis- 
souri. 
Wisconsin 






Chestnut oak 2. . . 


Tennessee . 


8.1 
11.4 


Tanbark oak 


California 


4,068 


Black oak 


.do... 


9.4 

8.3 
13.2 


112.4 

8.9 
' 11.9 


327 

309 
377 


1451 

294 
351 


/ 3,800 

1 1 4, 650 

3,960 

4 950 


Swamp oak 




9.5 
10.5 


Eucalyptus 


CaUfornia . . . 









1 Limbs. 

2 In case of chestnut oak the mean is not the average, since the slab represented more runs than heart. 

In yields of alcohol per cord, the different species of ash, tanbark 
oak, and eucalyptus are practically as good as beech and maple. 
Chestnut oak, swamp oak, slippery elm, and white elm (heartwood) 
did not compare so favorably with beech and hard maple, but all of 
them except chestnut oak gave higher yields than birch. 

Tanbark oak, California black oak,^ and eucalyptus are the only 
species in this group that gave as high yields of acetate of lime as the 
standard species, although swamp oak and chestnut oak gave prac- 
tically as good yields as hard maple. Tanbark oak gave a higher yield 
of acetate than any other species so far tested. The remarkable yield 
of acetate from California black-oak limb wood is due in part to the 
very heavy wood. It must be remembered, however, that commer- 
cially a cord of limbs would contain much less solid wood than a 
cord of body wood and the yield would be reduced proportionately. 

Table 3. — Relative yields of commercial alcohol and acetate per cord. 

["Average yield from heartwood of beech, birch, and hard maple from Indiana and Wisconsin=100 per 
cent. Acetate=316 pounds; aIcohol= 10.63 gallons.] 



Species. 


LocaUty. 


Alcohol. 


Acetate. 


Heart. 


Slab. 


Heart. 


Slab. 


White elm 




P6.0 
100.7 

80.0 
113. 7 

94.7 


78.1 

77.' 2 
85.6 
108. fi 


88.6 
87.3 
82.3 
82.9 


91.8 


Slippery elm 


Wisconsin 


83.2 


Silver maple . . . 


do 


69.3 




Tennessee and Missoiiri 

Wisconsin 


74.4 


Black ash 


82.3 


Green ash . . . . 


Missouri 


2 120. 7 


2 81.3 




Termessee 

California 


76.6 

106.7 

2 116.3 

89.2 
99.0 


82.5 

'"sh'.d 

78.4 
124.1 


90.8 

125.6 

2 142.7 

88.0 
102.8 


92.1 


Tanbark oak 




Black oak . . 


do 


103.5 






97.8 


Eucalyptus 


California 


119.3 









1 A more detailed discussion of the commercial possibilities of distilling the California 
oaks is given in Metallurgical and Chemical Engineering, Vol. XII, p. 623. 

2 Limbs. 



YIELDS FEOM DISTILLATION OF CERTAIN- HARDWOODS. 



The relative value of the species, obtained by taking the average of 
beech, birch, and maple heartwood as 100 per cent, is given in Table 
3, and the same values are shown diagrammatically in figures 1 and 2. 




^ GREEM,BLUE^ YELLOW ASH-TENH jiM0.-74.<^ 



BLACK ASH -WIS,- 82.3^ 



m 



i 



SLIPPERY ELM-WIS.-83.2 



; WHITE ELM -PA.- 91.8 



;CHESTNUT 0AK-TENM.-92.t 



mr 



SWAMP OAK -LA.- 97.8: 



mmi. 



BLACK 0AK-CAL.-103.S 



'mmmm. 



EUCALYPTUS -CALr 119.3 



m 



GREEN ASH -MC- 81 3 



I I M I I I I 



: BLACK OAK -CAL.- 142.7 



^mmmm 



25 



50 



too 



f25 



150 



75 
PERCENTAGE 

Fig. 1. — Relative yields of acetate of lime per cord. (Average yield from heartwood of 
beech, birch, and maple from Indiana and Wisconsin equals 100 per cent.) 



6 



BULLETIN" 508, U. S. DEPARTMENT OF AGRICULTURE. 



In Bulletin 129 the averages for beech, birch, and maple included 
yields from heartwood and lumber. Later experiments on tempera- 
ture control have shown that in these experiments yields from lum- 
ber were not strictly comparable with those from heartwood, and 




75 
PERCENTAGE 

Fig. 2.— Relative yields of wood alcohol per cord. (Average yield from heartwood of 
beech, birch, and maple from Indiana and Wisconsin equals 100 per cent.) 



YIELDS FROM DISTILLATION OF CERTAIN HARDWOODS. 7 

are therefore omitted in this bulletin. The data from Bulletin 129 
corrected to eliminate the yields from lumber are given in Table 4. 

Table 4. — Relative yields of commercial alcohol and acetate per cord. 



(Average yield from heartwood of beech, birch, and maple from Indiana and Wisconsin=100 
acetate=316 poimds; alcohol=10.63 gallons.] 


per cent; 


Species. 


Locality. 


Alcohol. 


Acetate. 


Heart. 


Slab. 


Heart. 


Slab. 


Beech 




111.0 
127.2 
78.2 
87.6 
111.0 
111.6 
88.4 
34.8 
144.2 
86.7 
86.7 
82.4 


102.6 
118.6 
83.7 
85.7 
109.3 
100.8 
86.7 
33.9 


95.3 
99.1 
109.5 
101.0 
95.3 
99.4 
85.2 
62.7 


106.0 


Do 


Pennsylvania 


106.7 


Birch. .. 


Wisconsin . . 


112.4 


Do 


Pennsylvania 


99.4 


Hard maple ^ 


W isconsin 


89 9 


Do 


Pennsylvania 


95.4 


Hed gum 


Missouri 


78.2 


Chestnut . . 


New Jersey 


60.2 


Hickory 


Indiana 




White oak 


do 


86.7 
95.2 
98.0 


97.7 
83.0 
71.6 


93.4 


Do 


Arkansas 


85.2 


Tupelo... . 


Missouri. 


82.4 









Elm and silver maple, which gave low yields of alcohol and acetic 
acid, also gaA^e low yields of liquor per cord. The cost of recovery 
per cord would, of course, be somewhat dependent on the amount of 
pyroligneous acid to be refined. 

The yields of charcoal and tar are only of relative interest. It was 
not possible in the laboratory tests to determine the value of these 
products, whose quality is only known in the wood-distillation indus- 
try in terms of commercial methods of distilling. In general, how- 
ever, it is noted that the heavier woods give higher yields of charcoal. 

PYROLIGNEOUS ACID, TAR, AND CHARCOAL. 

The average yields of pyroligneous acid, tar, and charcoal ex- 
pressed in pounds per cord are given in Table 5. The yields of 
pyroligneous acid are of interest mainly in connection with the cost 
of refining the products from a cord of wood. 

Table 5. — Average yields of pyroligneous acid, tar, and charcoal per cord. 



Species. 



Beech 

Birch 

Maple 

White elm 

Slippery elm 

Silver maple 

Green, blue, and yel- 
low ash. 

Black ash 

Green ash 

Chestnut oak 

Tanbark oak 

Black oak 



Swamp oak . 
Eucalyptus. 



Locality. 



Indiana 

Wisconsin 

do 

Pennsylvania . . 

Wisconsin 

do 

Tennessee and 
Missouri. 

Wisconsin 

Missouri 

Tennessee 

California 



.do. 



Louisiana. 
California. 



Pyroligneous acid 
(based on oven- 
dry wood). 



Lbs. 

1,062 

1,152 

1,120 

946 

984 

920 

1,162 

1,070 



1,280 
1,315 



1,089 



Lbs 

1,165 

1,159 

1,061 

997 

913 

809 

990 

1,040 



1,072 



1,125 
1,024 



l,405j 1,500 






Lbs. 

1,113.5 

1,155.5 

1, 090. 5 

971.5 

948.5 

864.5 

1,076 

1,055 
1,045 
1,176 



1,420 

1,056.5 
1, 452. 5 



Charcoal. 



Lbs 
1,417 
1,315 
1,341 

1,065 
1,180 
1,030 
1,410 

1.162 



1,425 
1,330 



1,598 
2,065 



Lbs. 
1,297 
1,284 
1,515 
1,055 
1,275 
1,115 
1,575 

1,234 



1,389 

1,630 
1,900 



03X2 



Lbs. 

1,357 

1, 299. 5 

1,428 

1,060 

1,228 

1,072 

1,492 

1,198 
1,388 
1,555 



1,640 

1,614 
1.982 



Tar. 



M 



Lbs 
319 
325 
418 
322 
279 
302 
390 

348 

'"368 
318 



Lbs. 
349 
285 
310 
295 
205 
201 
270 

276 
1346 
316 



Lbs. 
334 
305 
364 
309 
242 
252 
330 



312 
"342 



1413 

279 
271 



Lbs. 

3,785 

3,875 

3,600 

3,060 

3,330 

2,880 

3,960 

3,510 
3,960 
4,140 
4,068 
3,800 
14,650 
3,960 
4,950 



Limbs. 



8 BULLETII^ 508, U. S. DEPARTMENT OF AGRICULTURE. 

Where especially high yields of refined products are obtained, 
there is usually a large volume of crude liquor wliich must be handled 
to secure these products. Tanbark oak, California black oak, and 
eucalyptus all showed high yields of crude liquor per cord and also 
gave high yields of acetic acid and alcohol, as indicated in Table 2. 
use of the manufactures from figures 1 and 2. The laboratory yields 

COMMERCIAL DISTILLATION. 

The results given in this bulletin can be best interpreted for the 
use of the manufacturer from figures 1 and 2. The laboratory yields 
of acetate of lime are over 50 per cent higher than those obtained in 
standard commercial practice, although the alcohol yields do not 
differ much from commercial yields. 

Since the data are compared with the results of laboratory dis- 
tillations of the standard species — beech, birch, and maple — ^they are 
entirely comparable on this basis. In the commercial interpretation 
of these diagrams, the average yields per cord from Wisconsin and 
Michigan beech, birch, and maple may be given as 10.5 gallons of 
82 per cent crude wood alcohol and 185 pounds of gray acetate of lime. 
Using these yields as a basis, and taking the relations given in the 
diagrams, a simple calculation will give an actual cost value for 
judging the different forms and species for distillation. For exam- 
ple : Taking an average market value for acetate of lime as $1.75 per 
100 pounds and 82 per cent alcohol at 26 cents per gallon, the value 
of these two products ^ from beech, birch, and maple in the commer- 
cial plant is, then, $3.24 for acetate plus $2.73 for alcohol, which equals 
$5.97 per cord. Comparing chestnut oak in figures 1 and 2, the cal- 
culation gives $3.24X0.915 2-|-$2.73X0.796=$5.14. Chestnut oak is, 
then, obviously worth about 83 cents less per cord to the distillation 
plant than the standard species. The slabs alone are worth more than 
bodywood, a consideration of interest to the sawmill. Tanbark oak 
indicates a value of $3.24Xl.256+$2.73Xl.067=$6.98 for alcohol 
and acetate, or with equal manufacturing and market conditions, a 
plant could stand a charge of $4.50 per cord for the raw material. 

Of course, many other factors enter into the consideration of the 
value of any form or species of wood for distillation, but the relative 
value of the products examined would in each case be the primary 
consideration. 

1 In this particular calculation it is necessary to assume that the yields of charcoal 
would not vary greatly. If the calculation with acetate and alcohol indicated the value 
of the wood to be questionable, the charcoal could not be expected to bring up the result. 

2 Mean of heart and slab. 

O